The present invention relates to a postal security device (PSD) for use in a postage meter. More specifically, it relates to interfacing a PSD with a computer using only the keyboard port of the computer and one additional computer port.
The United States Postal Service has proposed an Information Based Indicia Program (IBIP) to replace the indicia (postmarks) printed by traditional postage meters. IBIP will use a two-dimensional symbol printed on the envelope to provide evidence that postage was paid, as well as providing additional information fields. This information is encoded into the symbol together with security information. The two-dimensional symbols can be thought of as an advanced version of the bar codes that are commonly used to identify products in supermarkets.
In contrast to traditional postage meters, in which all the indicia with the same postage value printed on a given day are identical, the indicia printed on each piece of mail using an IBIP symbol will be different. This will create a unique and traceable identity for each piece of mail.
A PSD is a security device that is used in conjunction with a host system to create the IBIP indicia. The PSD is implemented in hardware and provides a number of security functions, including cryptographic digital signature generation and verification. The PSD also maintains the descending register, which tracks the amount of postage available for postmark creation, and the ascending register, which tracks the total postage value used by a given PSD. These registers perform the same functions as the ascending and descending registers of traditional postage meters.
Postage may be loaded into the PSD, either at a post office or by a remote communications link. When this occurs, the descending register is updated to keep track of the amount of postage available for printing indicia. As the indicia are printed, the descending register is decremented to reflect the amount of postage that remains.
It is envisioned that PSDs will be used in a dedicated, stand-alone postage meter. It is also envisioned that PSDs will be used in conjunction with ordinary computers, in which case the indicia will be printed by ordinary computer printers. The security functions provided by the PSD will prevent the fraudulent printing of postage indicia.
The Postal Service's PSD specifications require the use of a data port connector and an authentication port connector that are physically distinct from each other. While Applicants are unaware of any commercially available PSD, a block diagram of a basic PSD that meets this requirement in a computer based environment can be readily envisioned.
FIG. 1 shows an example of such a PSD 11, connected to a computer 21. The PSD 11 contains a security controller 13, which provides the security functions of the PSD 11, including maintaining the ascending and descending registers, and generating digital signatures. The security controller 13 communicates with the computer via the data port 14 and the authentication port 15 which are, as required by the PSD specification, physically distinct.
The computer 21 includes a parallel port 22, a serial port 23, and a keyboard port 24. The parallel port 22 is connected to the data port 14 of the PSD 11 using an appropriate cable or connector. Similarly, the serial port 23 is connected to the authentication port 15 of the PSD 11 using an appropriate cable or connector. The computer 21 could be any suitable type of computer including, for example, IBM PC and Apple Macintosh computers (and compatibles). The keyboard 25 is connected to the computer 21 by plugging the end 26a of the keyboard cable 26 into the keyboard port 24 of the computer 21, to provide keyboard signals to the computer in a conventional manner.
The computer communicates with the data port 14 of the PSD 11 via the parallel port 22. Similarly, the computer 21 communicates with the authentication port 15 of the PSD 11 via the serial port 23. Both the PSD control program and the software in the computer 21 are configured to communicate using the appropriate port in a conventional manner. While FIG. 1 shows the use of one parallel port 22 and one serial port 23, any combination of ports may be used (e.g., two parallel ports), as long as the computer ports 22 and 23 and the PSD ports 14 and 15 are compatible.
While this configuration provides a workable PSD, one serious drawback is that it uses two ports of the computer 21. With many computer setups, however, the computer 21 will already be hooked up to various other devices using the ports 22 and 23, and the two required computer ports will not be available. In some cases it may be impossible to add addition ports, such as when all the expansion slots of the computer 21 are occupied. This is particularly likely to be a problem with laptop computers, which usually have limited expansion capabilities.
Even in those computer setups where additional ports can be added, it may be undesirable to add ports for a number of reasons. For example, many users are reluctant to open up their computers to install additional hardware. In addition, the set up required to add a port may be difficult, time consuming, or beyond the capabilities of the computer user.